


Impossible

by Interverse



Category: Undertale (Video Game)
Genre: Alternate Universe - Swapfell (Undertale), Alternate Universe - Underswap (Undertale), Cuddling, Fluff, Implied/Referenced Self-Harm, Light Angst, M/M, Self-Esteem Issues, Smoking
Language: English
Status: Completed
Published: 2020-05-21
Updated: 2020-05-21
Packaged: 2021-03-02 05:29:06
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,261
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23909986
Author URL: https://archiveofourown.org/users/Interverse/pseuds/Interverse
Summary: Stretch and Slim have fun pondering some existential paradoxes together, but the latter of the two lets it get to him maybe a littletoomuch.
Relationships: Honeybbq - Relationship, Papyrus/Papyrus (Undertale), Underswap Papyrus/Swapfell Papyrus
Comments: 2
Kudos: 15





	Impossible

**Author's Note:**

> A reupload from a previously existing oneshot book.

Slim squinted at the ceiling, trying to count all of the little bumps in the texture before quickly deciding that the headache the task gave him was not worth it. Instead, he searched for patterns. It was an activity he had grown to know well, as he’d done it ever since he was a babybones. At night, when he couldn’t sleep, or in the morning, when he felt empty and worthless until his brother came knocking at his door, each one of the sharp little noises sending jolts of purpose through his body.

He had practically memorized his entire ceiling, but it was more fun when he wasn’t in his room, but someone else’s. They weren’t too close, both splayed comfortably on Stretch’s bed, but they were holding hands; fingers laced tightly together and nestled into the folds of the old, worn blankets beneath them. It was enough. There was no need for words or any closer contact, and they were both perfectly content as they were, the other’s presence in any form satisfying.

Slim could still see the last of the haze in the air left from their previous activities. No matter how convincing the disapproving looks and sneers from Black were, he always seemed to bounce back to smoking; and had only gotten worse once he had gotten together with Stretch. Apparently Blue was much more forgiving, still disapproving but not bothering to do anything about it, so Stretch had a seemingly endless supply of smokeable goods that he was happy to share with his boyfriend. It helped. He felt less inclined to glance over his shoulder at laughably frequent intervals, was less compelled to pick at his scars until they bled, and was able to look in a mirror without being sent into a pool of self-loathing.

After thoroughly analyzing a section of the ceiling and concluding that it contained a moon and a tree, he moved on to another. This new area was proving difficult. Was that a leaf..? No… perhaps it was roots. Yes, that made more sense. But yet again… it did also resemble a-

“Hey, Slim?”

To his embarrassment, he jumped, face immediately flushing purple afterwards even though nobody was there to care or see. “Er… yeah?”

“So…” Stretch started slowly, “You know about all the possibilities with how many universes there are, right? I kinda think about it a lot.”

Slim hummed in affirmation, the simple vibrations taking less effort than the words he knew he would find a way to stumble over.

“So anyway if you think about it… _everything_ is possible, because there are so many places for things to happen, and all of those places have different rules, so there’s never something that could never happen. You know, like, no matter what.”

Another hum.

Stretch took a breath, squeezing his hand a bit tighter for a moment as well. “So… if anything and everything is possible… doesn’t that mean that it’s possible for something to be _impossible_?”

Slim sat there for a moment, tentatively rolling the information around on his tongue to better understand its flavor, and when he had finished, his eyesockets were stretching wide. “Holy shit…”

“I know, right?” Stretch said, voice seeming drowsy and excited all at once. “But then if something was impossible, it would take something away from the rule of everything needing to be possible!”

Slim squinted. “Maybe… maybe like… the thing that’s impossible is completely separate from everything else to the point that it like… isn’t even relevant in any universe or multiverse or dimension or whatever… so it doesn’t disrupt the rule?”

Stretch was silent for a few moments, then spoke again. “Okay… like… that could work… but again… if anything is possible, doesn’t that mean it would be possible for like… a specific thing to be impossible? I mean, if everything’s possible, then it would be possible for trees to be impossible, right?”

Slim didn’t like this notion one bit. “Wait… so… that means it’s possible for _everything_ to be impossible, too. It’s possible that the entire fucking rule is a lie and nothing is possible and this is all just an illusion- but wait illusions aren’t possible either- _fuck_ -!” he finished, deflating.

Stretch groaned. “Man, this is fuckin dumb.”

Yet another hum, clearly depicting Slim’s agreement. Silence filled the room again, warm and comforting and seeming to cradle the both of them without judgement or hesitation. Slim would have been unhappy that the quiet was chased away if a different monster was responsible, but his lover’s voice swam through his skull with a gentleness that no sound other than the lack of it could achieve.

“Sorry in advance… but I uh… I have another one.”

“Shoot.”

Stretch sucked in a breath of air in preparation for speech. “Alright, so, light speed. Three hundred million whatever whatevers per whatever or some shit in a vacuum, right?”

“Yeah.” _299,792,458 meters per second in a vacuum_ , to be exact, but Stretch’s explanation was sufficient enough.

“So, okay, say you’re just ambling along at light speed or whatever-”

“But you can’t,” Slim interjected, his love of such things taking priority over his instinct to let his partner finish. “You have mass, and light speed is impossible unless the thing going at said speed is massless.”

“I know, I know,” Stretch scoffed gently. “But just say that you were, okay? Decided you wanted a new look so you convert your entire body into photons or somethin.”

“Alright,” Slim relented.

“Okay, so then you have a flashlight, also, uh, massless, and you turn it on.”

“Flashlight is on. Got it.”

Stretch huffed. “You’re already traveling at light speed, so… the new light from the flashlight… how fast is it going? Does it just take a giant shit on the rules of the universe and go twice the speed of light?”

Slim furrowed his browbones. Clearly, this situation would never present itself in reality, but… if it did… “I… don’t know…” He thought for another moment. “Maybe… what if the light still went at the speed of light, so it just didn’t go anywhere and hung out right at its source. Like a little light pool.”

Stretch chuckled. “I bet it would be super expensive to swim in. Heh, or maybe the universe would just give the entire situation a giant middle finger to the face and make it all collapse into a black hole.”

Slim nodded to the best of his ability from his position. “Black holes always solve paradoxes.”

More silence, then more soft speech. “Hey, cummere.”

Slim felt a little tug on his hand, so he disentangled it from Stretch's, then rolled over until he was nestled into his alternate’s side. He rested his head on the other’s shoulder, squeezed an arm underneath him, and twined their legs together with a sigh. Stretch was warm, not to mention soft and familiar and _safe_ , so it was no surprise Slim was drifting off to sleep in a matter of minutes.

“Hey. You know I love you, right?”

That woke him up. “I… yeah… I know…” he whispered after a few seconds, squeezing his companion tighter for a moment. He swallowed. “...So I guess it’s possible for it to be impossible that you’re tellin the truth, huh?”

Stretch shushed him. “I thought we agreed to let all that bs alone.”

Slim breathed in. The other smelled of honey and smoke and something else that he couldn’t give a label, but it sent a shiver down his spine all the same. “...I love you too.”


End file.
